Proactive Reservations of Network Address Blocks for Client-Specified Operation Categories at Isolated Virtual Networks

1. A system, comprising: one or more control plane servers of a virtualized computing service, wherein the one or more control plane servers include one or more hardware processors and one or more memory devices, and the one or more memory devices store program instructions that are executable by the one or more hardware processors to: in response to receiving a first reservation request, store metadata indicating that a first sub-range of a range of network addresses of a subnet established within an isolated virtual network is reserved for fulfilling requests of at least a particular category of a set of request categories, wherein the set of request categories includes (a) bulk address assignment and (b) client-requested individual address assignment; in response to receiving a first address assignment request, generate a response message indicating rejection of the first address assignment request, wherein the rejection is caused based at least in part on a determination that (a) assignment of a particular address of the first sub-range is requested in the first address assignment request and (b) the first address assignment request does not belong to the particular category, wherein the first address assignment request is received and rejected during a time interval in which the particular address is not in use within the isolated virtual network; and in response to receiving a second address assignment request, wherein the second address assignment request belongs to the particular category, configure a particular device within the isolated virtual network with one or more addresses of the first sub-range.

2. The system as recited in claim 1, wherein the second address assignment request is a bulk address assignment request, wherein the one or more addresses of the first sub-range assigned to the particular device comprise a contiguous group of addresses, wherein the bulk address assignment request does not specify the contiguous group of addresses, and wherein the program instructions are executable by the one or more hardware processors of the one or more control plane servers to: select the contiguous group of addresses from the first sub-range.

3. The system as recited in claim 1, wherein the first sub-range comprises one of: (a) Internet Protocol Version 4 (IPv4) addresses, or (b) Internet Protocol Version 6 (IPv6) addresses.

4. The system as recited in claim 1, wherein the program instructions are executable by the one or more hardware processors of the one or more control plane servers to: store, in response to a second reservation request, additional metadata indicating that a second sub-range of the range of network addresses of the subnet is reserved for fulfilling requests of at least the particular category.

5. The system as recited in claim 1, wherein the program instructions are executable by the one or more hardware processors of the one or more control plane servers to: store, in response to a second reservation request, additional metadata indicating that a second sub-range of the range of network addresses of the subnet is reserved for fulfilling requests of a category other than the particular category.

6. A computer-implemented method, comprising: in response to receiving a reservation request, storing metadata indicating that a sub-range of a range of network addresses of a subnet configured on behalf of a client of a provider network is reserved for operations of a particular category; in response to receiving, at the provider network, a first request for a first operation, generating a response message indicating rejection of the first request, wherein the rejection is caused based at least in part on determining that (a) the first operation comprises assignment of a particular address of the sub-range and (b) the first operation does not belong to the particular category, wherein the first request is received and rejected during a time interval in which the particular address is not in use; and in response to receiving a second request for a second operation, wherein the second operation belongs to the particular category, configuring one or more devices with one or more addresses of the sub-range.

7. The computer-implemented method as recited in claim 6, wherein the second request is a bulk address assignment request, and wherein the configuring of the one or more devices comprises configuring a virtual network interface with a contiguous group of addresses.

8. The computer-implemented method as recited in claim 7, wherein the bulk address assignment request is directed to a virtualized computing service, wherein the bulk address assignment request does not specify the contiguous group of addresses, the computer-implemented method further comprising: selecting, by the virtualized computing service, the contiguous group of addresses from the sub-range.

9. The computer-implemented method as recited in claim 6, wherein the second request is a client-requested single address assignment request submitted by a client of the provider network, and wherein the configuring of the one or more devices comprises configuring a virtual network interface with a single address.

10. The computer-implemented method as recited in claim 6, further comprising: providing, via a programmatic interface, an indication of a number of in-use addresses of the sub-range.

11. The computer-implemented method as recited in claim 6, further comprising: storing metadata indicating that another sub-range of the range of network addresses of the subnet is reserved for operations of one or more categories; and in response to another request of a category of the one or more categories, configuring a device with an address of the other sub-range.

12. The computer-implemented method as recited in claim 6, further comprising: in response to a reservation deletion request, delete the metadata indicating that the sub-range is reserved; and in response to receiving, after deleting the metadata, another request for another operation of a category to which the first operation belongs, configuring a device with an address of the sub-range.

13. The computer-implemented method as recited in claim 6, wherein the reservation request indicates a size of the sub-range, and does not specify the sub-range, the computer-implemented method further comprising: selecting the sub-range at a computing service to which the reservation request is directed, wherein the selecting is based at least in part on the size of the sub-range and a configuration of the subnet.

14. The computer-implemented method as recited in claim 6, wherein the sub-range comprises one of: (a) Internet Protocol Version 4 (IPv4) addresses, or (b) Internet Protocol Version 6 (IPv6) addresses.

15. The computer-implemented method as recited in claim 6, further comprising: determining, at a service of a provider network, that a network address selected by the service is to be assigned to fulfill a service request; and selecting, by the service, the particular network address to fulfill the service request, wherein the first request is generated by the particular service.

16. A non-transitory computer-accessible storage medium storing program instructions that when executed on a processor cause the processor to: in response to receiving a reservation request at a provider network, store metadata indicating that a group of network addresses is reserved for operations of a particular category, wherein the group comprises a subset of network addresses associated with a virtual network of a client of the provider network; in response to receiving, at the provider network, a first request for a first operation, generate a response message indicating rejection of the first request, wherein the rejection is caused based at least in part on a determination that (a) the first operation comprises assignment of a particular address of the group and (b) the first operation does not belong to the particular category, wherein the first request is received and rejected during a time interval in which the particular address is not in use; and in response to receiving a second request for a second operation, wherein the second operation belongs to the particular category, configure one or more devices within the virtual network with one or more addresses of the group.

17. The non-transitory computer-accessible storage medium as recited in claim 16, wherein the second request is a bulk address assignment request, and wherein the configuration of the one or more devices comprises configuration of a virtual network interface with a contiguous plurality of addresses.

18. The non-transitory computer-accessible storage medium as recited in claim 16, wherein the second request is a client-requested single address assignment request submitted by the client, and wherein the configuration of the one or more devices comprises configuration of a virtual network interface with a single address.

19. The non-transitory computer-accessible storage medium as recited in claim 16, storing further program instructions that when executed on the processor cause the processor to: provide, via a programmatic interface, one or more metrics pertaining to the group of network addresses reserved in response to the reservation request.

20. The non-transitory computer-accessible storage medium as recited in claim 16, storing further program instructions that when executed on the processor cause the processor to: store, in response to an operation category creation request from the client of the provider network, an indication of a custom category of operations; and store additional metadata indicating that another group of network addresses is reserved for operations of the custom category.